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MathGroup Archive 1998

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Re: (a-b)/(c-d)=!=(b-a)/(d-c) ???

  • To: mathgroup at
  • Subject: [mg13023] Re: [mg12964] (a-b)/(c-d)=!=(b-a)/(d-c) ???
  • From: "Jrgen Tischer" <jtischer at>
  • Date: Tue, 30 Jun 1998 00:26:21 -0400
  • Sender: owner-wri-mathgroup at

Hi Tim,

"SameQ requires exact correspondence between expressions, except that it
considers Real numbers equal if their difference is less than the
uncertainty of either of them." (Help of SameQ)

Exact correspondence means same FullForms of the expressions.


-----Original Message-----
From: Tim Dellinger <tdelling at> To: mathgroup at
Subject: [mg13023] [mg12964] (a-b)/(c-d)=!=(b-a)/(d-c) ???

>How come
>(a-b)/(c-d) === (b-a)/(d-c)
>returns False, i.e. TrueQ[ (a-b)/(c-d) =!= (b-a)/(d-c) ]  returns True,
>(a-b)/(c-d) === Simplify[ (b-a)/(d-c) ]
>returns True ???
>Why does mere simplification change anything? I'm using Mathematica
>3.0.?  on win95.
>"Perhaps my most deeply rooted hobby is to understand         Tim
> the mechanisms of simple and familiar
>tdelling at
> natural phenomena." Irving Langmuir

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